Existing ion mobility separators generally operate in-line with the ion optical path of a mass spectrometer and so have a direct impact on the overall length of the instrument and also must be transited even if ion mobility separation is not required, potentially making timing between rapidly changing ion signals and subsequent analysers more problematic. This becomes more problematic as the length of ion mobility separator is increased in order to increase the resolution of the device.
It is known to separate ions in closed-loop separators in order to overcome the problem of having to provide a relatively long device in order to obtain the required resolution. However, it is desired to provide an improved technique for introducing and extracting ions from such a device and also for causing ions to begin to move around such a device.
It is desired to provide an improved method of introducing and ejecting ions from an ion mobility separation device, an improved ion entry/exit device, and an improved mass spectrometer or ion mobility spectrometer.